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DURHAM, N.H. -- A University of New Hampshire space
scientist is among the researchers who have detected the
remnant of one of the closest, most recent supernova
explosions yet.

It's also one of the more mysterious, says James Ryan,
professor of physics in the university's Institute for the
Study of Earth, Oceans and SpaceInstitute for the
Study of Earth, Oceans and Space. Ryan and his
colleagues used the UNH-directed COMPTEL imaging
telescope aboard NASA's Compton Gamma Ray
Observatory to study the supernova remnant's titanium
gamma ray emissions, a new technique for finding young
supernovae remnants (SNRs).

Occurring 680 years ago and a mere 650 light years away
(for perspective, our Milky Way galaxy is 50,000 light
years wide), the supernova or exploding star was close
enough to be seen on Earth, but the question remains, did
anyone see it?

There are no written records of a bright light, outshining
everything in the night sky except the moon. The
supernova explosion certainly was close enough within the
Milky Way to be seen by medieval astronomers. And
previous supernovae were recorded in the years 1054,
1574 and 1604.

Ryan's colleagues at the Max Planck Institute, the Space
Research Organization of the Netherlands and the
European Space Agency guess the supernova may have
been optically obscured by material between the Earth
and the supernova. Another possibility is that the position
or time of the event may have been unfavorable; perhaps
it was too cloudy to observe the event.

Ryan points out the location of the remnant is minus-45
degrees latitude. So, it could only be well observed by
people in the Southern Hemisphere, not in Europe or Asia.
"Who was there to see it?" asks Ryan. And would those
who did witness the bright light in the sky document it?

Ryan and his team have used data from the COMPTEL to
study recent supernovae before, almost all in distant
galaxies, millions of light years away. In these cases,
COMPTEL analyzed the cobalt emissions from the
exploding star, since cobalt decays rapidly and gives off
a more intense emission. In other words, it's easier to
"see" from a distance.

For this closer SNR, titanium was analyzed. Titanium also
is produced in the high energies of a supernova explosion,
and as it decays, like cobalt, it emits gamma rays.
However, because titanium has a half-life of about 90
years, it is best used to detect SNRs hundreds of years
old.

In general, gamma rays can penetrate through the dust
and gas associated with supernova explosions, so we can
detect these high energy wavelengths more easily than
optical wavelengths. Thus, titanium gamma ray emission
serves as both a clock and a beacon for observers on
Earth.

Ryan says this latest find is significant because it
involved a supernova remnant "in the neighborhood," our
own galaxy. "There are very few supernovae seen
optically in our galaxy," he points out. "And it provides us
with dynamic information about the supernova process
and the life cycle of a star."

Note: Jim Ryan is unavailable for comment until
Friday, Jan. 8. He can be contacted at 862-3510.
In the meantime, his colleague, Mark McConnell of
the Space Science Center, can provide comment. His
number is 862-2047.